The present invention relates to a method for the generation of a nearly monodispersed aerosol in filter-testing machines.
For several decades, the U.S. Army has produced hot smokes using dioctyl phthalate (DOP) as the standard material in the performance of nondestructive gas mask and filter serviceability testing. Hot smokes are aerosols produced using a method of thermally-generated vaporization and recondensation (self nucleation) of particles. Heated air passes across the surface of a heated liquid (DOP), cooler air then merges with the vapor, causing recondensation of an aerosol or "hot smoke."
Recently, a new generation of smoke penetrometers have been developed which utilize the generation of cold smokes or cold aerosols. Cold smokes are aerosols generated by the process of pressurized nebulization aerosol generation. This process produces an aerosol which is thermally more stable than a hot smoke. The U.S. Army Surgeon General has designated DOP as a suspected carcinogen and has prohibited or severely restricted its use in smoke-generating machines used to test U.S. Army masks, respirators, filters and other personnel protection equipment.